Near-eye displays include whole-image-projection type displays and retinal beam-scanning displays. HUD-type image-projection displays essentially utilize a 2D panel display (or beam-written screen) of some sort and bulky relay optics and mirrors to pass the entire 2D image from the source display to the user's eye(s). Typically, the source of the 2D image is a small 2D SVG, XGA, UXGA or HD multipixel source display mounted on the side of the user's head along with a bulky optics train comprising several lenses and mirrors that are used to relay the projected 2D image from the image-display source to a semitransparent half mirror placed in front of the user's eye. Frequently, the HUD artificial-image content is displayed at a comfortable distance (under 1 meter to infinity) as perceived by the user; thus, the complex lens train is required. Head-up Displays (HUDs) of this type originally were developed for military fighter pilots and are in current use, such as in the Apache gunship and in many civilian aircraft. All such HUD displays relay the entire 2D image space of a real source display to the eye in a manner which makes it appear to the user that the content of the HUD display is projected upon the real surroundings or is projected adjacent to the surroundings. HUDs can allow visualization of both artificial HUD display data content such as aircraft instrument readings as well as of the real surroundings if a semitransparent projection surface is used or if the two image types do not overlap within the field of view. It is exceedingly difficult to provide bright, high-resolution HUD images and compactness as well as light weight and low cost at the same time. The brightness issue is particularly difficult in surrounding bright sunlight.
It is important to recognize that whether the HUD source display (the display whose image is relayed via optics) is a conventional 2D LCD or OLED display with frame-wise updates or is a laser or LED beam-written display using a pixel-by-pixel scanning beam, the entire 2D source-image space always is imaged by the HUD lens train which utilizes refractive (or diffractive) lenses and mirrors which simultaneously optically convolute then deconvolute the entire object image into the observed destination image. Typically, the source display has image persistence or significant emission duty cycle such that the entire display frame is always visible to the human user's eyeball which has its own fusion persistence. So, the key point is that with HUDs the eye sees an image which is refreshed as a whole, at least full pixel lines at a time, as opposed to being serially written pixel by pixel without display persistence. That requires the relay lens train to handle the ray traces coming from all the source pixels simultaneously in the form of a complete image or line of pixels which is convoluted then deconvoluted by the lenses in the known manner of conventional geometric optics and at any instant spans the entire lens diameter.
Retinal beam-writing displays, known as Virtual Retinal Displays or VRDs, rather than simultaneously relaying a whole 2D image of a real source display to the eye(s), serially write, pixel by pixel, the 2D image upon the retina(s) directly. There is no real 2D physical source display involved and therefore no source display persistence, but instead a micromechanical or MEMs-type 2D-mirror beam scanner scans a computer-controlled, dynamically changing, single writing beam fed by combined modulating red, green and blue lasers or LEDs. In this type of display, the image serially enters the eye pixel by pixel to the retina, and the projection geometry upon the retina is very dependent upon the angles through which the writing beam is scanned and upon the proper placement of the VRD's exit pupil at or within the user's eye entrance pupil. Typically the VRD eye-entering sequentially placed beams are divergent from each other inside the eye, resulting in a retinal image that is significantly larger than the eye pupil itself. Such VRD displays typically are lighter and more compact than HUDs, however the scanning mirror(s) and ganged primary red, green and blue light sources and the color combiner(s) can be expensive and fragile and the user's eye pupil must overlay the VRG's exit pupil at all times in order to see the scanning VRD image-writing beam. Note also that eye movements or any unintended vibration of the steering mirrors can result in image distortions during the writing of a single-image frame upon the retina.
Display of fast-moving video also can be an issue for VRDs as pixel-by-pixel beam writing is much slower than the 2D image-wise projection of HUDs. We specifically point out that the VRD beam scanner directs its single angulating scanning beam through any intervening lenses or mirrors (usually numbering fewer and smaller than for HUDs) as a single, small, low-divergence beam such that at any moment there is no light-ray convolution and deconvolution (as for 2D whole-image formation through lenses) as there is for the HUD optics which pass entire 2D images at a single instant. Thus, the VRD beam is of very small diameter (typically less than 1 mm before pupil entrance), of near zero divergence (ideally less than a couple minutes of arc) and it will often be even smaller in diameter upon retinal impact due to the additional focusing effects of the user's cornea and lens. The takeaway point here is that, at any moment, only one very narrow scanned beam passes through a very tiny portion of any lenses such that there is no full-image convolution and deconvolution occurring as the beam follows a unique raytrace path through the lenses.
Herein we combine these seemingly incompatible technologies to provide a massively parallel beam-writing display wherein each intended retinal image pixel is written and updated by its own spatially static, properly directed and dedicated pixel beam. Note that in our invention “writing” on the retina is really rewriting (constant updating or exposing) of fixed pixels in fixed positions each by dedicated, static pixel beams and not by spatial rastering of a shared beam. A 2D, physical source display preferably still is employed, however this display can be very small, curvilinear or flat, and mounted close to the eye as upon a structure such as an eyeglass frame that is in the field of view. The inventive displayed image appears large and in focus despite the source display being physically so close to the eye. In order to achieve this, our multipixel source display, typically within the user's field of view and near the eye, has the emanating light from each of its pixels independently and substantially simultaneously directed to its respective intended retinal image location along dedicated raytrace paths. By “substantially simultaneous” we mean truly simultaneously or with delays between pixel exposures that are so short within an image frame (nanoseconds, for example) that the user senses no delays, yet the delays are long enough (not zero) to prevent adjacent-pixel diffractive interference if monochromatic light is involved.
We provide the following definitions to assure that our meanings are clear herein.
Definitions
1) Multiple-pixel-beam retinal display or MPBRD:
A multiple-pixel-beam retinal display (MPBRD) is a near-eye (or on-eye) display system in which an image source display has its image beamed into a user's eye in the form of a simultaneous bundle of spatially independent, nonmoving pixel beams, one pixel beam emanating from each source-display pixel. The pixel beams are each low-divergence, small-diameter beams such that they each follow a unique spatial path from their source-display pixel at least to the vicinity of the display exit pupil. In this manner, and unlike conventional 2D images being passed through convoluting and deconvoluting lenses, any lenses utilized pass only the separate pixel beams. Thus, the light coming from each source-display pixel is passed separately along independent spatial paths to the region of the user's eye entrance pupil. What the MPBRD has in common with VRDs (virtual retinal displays) is the use of pixel-wise beams steered to retinal targets, but millions as opposed to one and static as opposed to scanning. What the MPBRD has in common with HUDs is the use of a 2D source display but without the bulky conventional image-relay optics train. The MPBRD allows a high-resolution, video-capable source display to be placed very close to the eye (e.g., 0-25 mm) yet appear at an apparent perceived comfortable distance of under a meter to infinity while avoiding bulky and expensive lens trains. Special measures must be taken to assure that the light from each of the source-display pixels is passed individually to the vicinity of the eye's entrance pupil as spatially unique—yet simultaneous—pixel beams. These measures are associated with forming low-divergence pixel beams and then steering each one at the proper, unique, fixed angles and offsets to its dedicated, fixed retinal target. Typically, the MPBRD will have its numerous simultaneous beams (versus sequential scanned beam in the VRD) diverge inside the eye to expose an image on the retina which is significantly larger than the eye's pupil diameter. In addition, and also unlike a VRD, the MPBRD also is capable of delivering an approximately parallel or somewhat divergent beam bundle(s) into the eye in cases wherein a smaller image(s) on the retina is sufficient and is the design goal.
MPBRD(s) may be worn on one eye or on two eyes. Two-eye systems can present 3D as well as 2D image content such as by using known eye shutters or polarizers to achieve perceived stereo imagery.
The MPBRD display also may have connectivities to complementary external devices and services in addition to its own internal connectivities to, for instance, sensors, cameras, displays, data, CPU, GPU, power and memory. The MPBRD itself likely will include forward-looking video cameras, smartphone functionality, audio in/out support, GPS, magnetic compass, eye-gaze-determination, inertial and/or head-orientation sensors, and also may include interfaces to wired and wireless networks or external hardware connections such that an overall communication and awareness system is provided, and that system and its user can talk to or communicate with other devices, data sources or persons.
2) Static or angularly fixed pixel beams:
For MPBRDs, static or angularly fixed pixel beams can refer to any one of the following:                a) static or fixed relative to other pixel beams in the bundle long enough for one image frame to be presented,        b) static or fixed relative to other pixel beams in the bundle for a period long enough for several image frames to be presented, or        c) static or fixed until an overall image-format change is made, such as a retinal image-size change, retinal image position or retinal image resolution change, after which the pixel beams are again static and fixed.        
3) Optical-coupler element: (typically employed as a standalone element or co-integrated into an emitting source-display pixel)
An optical-coupler element at least gathers the emanating light coming from a source-display pixel, typically into a smaller divergence beam. If the display pixel already has a small divergence beam, then use of a separate coupler may be avoided. A primary goal of a coupler is to prevent the waste of pixel-output emissive energy by catching as much of it as possible. However, a portion of the pixel's emissive output power in the periphery of the beam may be excluded intentionally in order to pass onward a lower-divergence output.
4) Beam-divergence-limiting element: (typically employed as a standalone element or co-integrated into an emitting source-display pixel)
A beam-divergence-limiting element assures that the beam divergence of each coupled pixel beam is or becomes small enough (preferably a few arc minutes or less) such that the user discerns an overall retinal image with useful contrast despite closely bundled beams. A multihole, multifiber or multichannel collimator may both limit divergence of each pixel beam and usefully create or maintain an organized bundle of directed independent pixel beams such as a parallel, converging or diverging bundle of pixel beams, with each pixel beam having less than the maximum allowed angular divergence. A microlens array such as a GRIN lens array or shaped refractive or diffractive microlens array could provide the same divergence control and bundling in the same manner in a smaller space. The holes, fibers, light channels, light conduits or lenses may have any solid, liquid, gaseous or vacuum makeup or structure regardless of whether it is an integrated structure, such as a microcapillary hole array, or many individual structures, such as the microlenses of a microlens array. Use of reflective elements such as an array of shaped reflectors also is possible. A primary goal of the beam-divergence-limiting element is to establish sufficiently low-divergence pixel beams that each then can be steered to its individual retinal destination by a beam-directing element yet maintain their spatial contrast at the retina.
5) Beam-directing element: (typically employed as a standalone element or co-integrated into an emitting source-display pixel)
A Beam-directing element contributes to the directing of pixel beams. The primary beam directing element of the invention individually steers or directs pixel beams toward their respective different retinal spots. A secondary beam-directing element may be offered by the above beam-divergence limiting element such as if it also forms or directs a parallel bundle of low-divergence pixel beams each having a translational offset relative to its neighbor. The directing element typically may be, for example, any one or more of a lens, prism, mirror or optical conduit or arrays of these. By “individually steered” it is meant that the many low- or no-divergence, simultaneous pixel beams in the bundle are differently, statically directed to form a converging, parallel or diverging bundle of such pixel beams as they approach the display exit aperture and the eye entrance pupil, with at least some of the converging, parallel or diverging pixel-beam bundle passing through the overlaid user's eye-entrance pupil, the passing beam bundle, upon arrival at the retina, forming a retinal image of some or all of the source image.
6) Convolution/Deconvolution:
Conventional optical lenses pass entire images in a manner wherein at points between the source object being imaged and the destination focal plane, the millions of ray traces coming from the millions of object points cross paths. No good image can be obtained at these intermediate positions and this state is called convoluted. Only at the destination focal plane has the lens then also applied its deconvolution to reestablish the recognizable image. This action of the lens also is described by its transfer function. When a desktop display is viewed, the display image likewise is convoluted and then deconvoluted as it passes through the user's eye cornea and lens to the retina. The invention of the MPBRD avoids convolution and deconvolution as it forces the light from each source pixel to travel a dedicated pixel-beam path without mixing with or crossing other pixel-beam paths on the way to the vicinity of the user's eye pupil. It also allows easily for achieving an apparently infinite, or closer but comfortable, working distance, if that is desired, without use of a complex lens train.
7) Source Display: (typically employed as a 2D, multipixel, flat or curved display whose emitted light is produced by the pixels or whose pixels are lamp, LED or laser backlit and possibly backlight-switched at the pixel by a shutter. Even front-illuminated reflective pixels are possible.
The flat or curved multipixel source display creates the 2D source image which then is passed to the retina as a bundle of dedicated pixel beams. Before the beams reach the display exit pupil they preferably do not overlap or cross paths. The source display may be flat or curved and may utilize any known or future display technology including, for example, those based on emissive and/or backlit LCD, LED, laser, plasma, OLED (organic light emitting diode, also including PLED polymer light emitting diode and AMOLED active matrix organic light emitting diode), quantum dot and electron microemitter and cold or hot field-emission technologies. Of particular applicability to the invention are: (a) OLED displays because they are very bright, have superb color gamut, can be made readily in small sizes and can be curved easily in one or more directions. They also can be transmissive to allow viewing through the display and (b) surface laser or VSCEL type displays, which inherently have very high brightness, narrow beams in at least one direction, (c) laser-backlit or pulsed-LED backlit displays using SLMs or shutters to gate the emitted light, which may also be highly directed and (d) plasma display technology.
Of particular interest and applicability are displays having very small pixels such as those used in HD camcorders or SLR viewfinders. These can have pixels which measure as small as 5 to 30 microns in maximum dimension. Included herein as well are displays which have pixel-by-pixel dedicated color filters as well as displays without any pixel filters, which instead use multicolor-laser, backside illumination of all pixels and an overlying spatial light modulator (SLM) to activate pixels. Future source displays probably will include quantum dot displays, an area of active research today. Even very low-profile CRT and laser-based, scanned-source displays are possible and have been proven for full-size and proportionally very thin televisions. The common trait of all possible source displays is low profile, i.e., the source-display thickness is small compared to its lateral viewing dimension. Typically, the source display will be available as a module, will be separately testable, and will have its own internal interconnections, switching and shift registers for activating pixels as do known 2D displays such as those used in TVs, cellular phones, smart phones, tablets and e-book readers. Even brightly lit e-paper-based book-reader-type displays could be used. We explicitly include source displays which have been specifically optimized for this invention as discussed herein. In some cases the source display will be cofabricated with or directly integrated during manufacture with one or more of the taught optical elements such as optical couplers or optical divergence limiters and directors. In particular, it is possible to cointegrate the source display and the divergence-limiting components, because divergence-limiting microcapillary or optical-conduit arrays have physical holes or defined cavities, respectively, which can be utilized as plasma or lasing chambers or have conduit refractive indices and dielectric constants which can support known light-emitting resonance behaviors.
8) Display Connectivity:
Wired, wireless and plug-in connections enabling connectivity to external entities such as standalone products, complementary products, display-supporting peripherals or display-supporting services, including, for instance, any type of: PCs, laptops, tablets, cellphones, smartphones, landline phones, music and/or video players, video or audio recorders, still or video cameras, GPS navigators, electronic mapping devices, disk drives, solid-state drives, dongles, plug-in memory cards or sticks, routers, servers, access points, vending machines, toll-taking kiosks, wired or wireless connections to external electronic devices such as via WiFi, USB, HDMI, VGA, RS232 or FireWire, network, optical links such as IrDA, radio-based connections, Bluetooth, satellite network or channel, cable TV network or channel, personal or employer security system. The purpose(s) of such connectivity could be many including inventive display uploads, display downloads, display user communication with other persons or with or via online services, display connection to the internet or directly to another person's device, or the use of an external television or smartphone to show live or recorded display images (surroundings and/or data images) or the use of a video recording device to externally save or broadcast a live or recorded data stream sourced from the display. Connectivities to automobile and vehicle electronics and networks also are anticipated. Such connectivities may be used occasionally or regularly, with or without the display user's live attention. We include external power connection when and if internal power is not used.
9) Display Services:
These are services which are free or paid for, voluntary or involuntary and which may or may not require an enabling connection from above or from a provider. Services may include such as: Internet connection service, cellular phone and/or cellular data service, satellite services, broadcast services, cable-based services, GPS services, search services, email or texting services, social network services, mapping and street view services, cloud-based services, data storage and/or backup services, data retrieval services (such as for display data overlays), advertising whether situational or not, subscription services, software or hardware licensing services, educational or instructive services, website creation or maintenance services, retail or vending services, travel services, gaming services, entertainment services, people/place finding and lookup services, dating services, navigation services, electronic wallet services, or any of speech/speaker/text recognition services